SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50fab021cf36738970114adb9ab28865855fdbb29c5d397acac3c42494e67c86' 
  AND token = 'Zr6vjnvZEtDyWOq7SAWH60/FQysowKcg+w2hs68nn4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}